The invention is directed to a method and apparatus for handling electrical components and particularly to selecting and fetching leadless and leaded surface mountable electrical components in a particular sequence and to mounting the sequenced components on a printed circuit board (PCB) automatedly in a chip placement process.
Chip placement generally involves surface mounting of miniature components, without the need for lead receiving holes at the mounting locations of the circuit board and usually by using a dot of glue to hold the component on the circuit board in preparation for subsequent soldering of electrical connectors of the component to the electrical tracks. The thickness of these surface mounted components generally range from 0.018-0.062 inches, with width and length dimensions perpendicular to the thickness generally ranging from 0.040-0.250 inches. The electrical connectors of surface mountable components may comprise: conductive pads which are generally flush with the component body; hemispherical-shaped conductive balls; and/or conductive leads protruding from the body. The tips of the protruding conductive leads may extend past or be generally flush with a surface of the component body which is adjacent and generally parallel to the circuit board top surface when mounted.
Accordingly, it is an object of this invention to provide a method and apparatus for increasing the population capacities and speeds of chip placement machines while providing for handling of surface mountable components of the type having leads, as well as the leadless type.
Another object of the invention is to provide a method and apparatus for detecting a defect at a placement station wherein a component is missing, tilted, or an incorrect thickness and performing a high speed repair function to replace the particular component while the circuit board is still at the placement station.
An additional object of the invention is to provide an improved chip carrier which is spring mounted to a conveyor chain for alignment positioning relative to and parallel to the direction of the path of travel of the conveyor. The chip carrier is provided with a clamp arm for holding the component on a pad thereof without interfering with any leads which the component may have, and the pad is porous to facilitate negative and positive air pressures, respectively, for holding the component on and displacing the component from the pad selectively.
These and other objects and advantages of the present invention will be more clearly understood by reference to the following description and drawings.
The present invention involves a method and apparatus for feeding leadless and leaded surface mountable components directly from a sequencer to a chip placement head. An endless chain conveyor carries the sequence of components to a chip placement head via a series of chip carriers, each chip carrier having negative air supplied thereto during loading to hold a component and positive air supplied during unloading to aid in removal therefrom. Direct supply from a sequencer having a series of individual programmably controlled dispenser heads provides for quick and flexible variation of an input sequence without manual intervention. A turret assembly has multiple chip placement heads which unload the chip carriers and facilitate orienting, centering, and squaring of the components prior to placement on a circuit board.